1. Field of the Invention
This invention relates generally to an evaporative humidifier pad for furnace and recirculating type humidifiers, and more particularly to the construction of the pad and the method by which the pad is constructed.
2. Description of the Related Art
Household humidifiers commonly have replaceable evaporative elements that spread water over a surface to promote evaporation of the water into air that is directed over and through the element. It is known that an element should permit air to freely pass through the element, and that the element should have a large surface area for exposure of the water to the air. It is also known to make the evaporative element from materials that will promote capillary or wicking action to absorb and spread the water throughout the evaporative element.
In addition, the evaporative element should be made of materials and with a configuration sufficient to maintain the structural integrity of the evaporative element when it is subjected to use in water, heat and air flow. The prior art contains humidifier elements with reinforcing material placed between paper layers, such as in U.S. Pat. No. 5,374,381 to Schuld et al., which patent is incorporated by reference herein. Additionally, U.S. Pat. No. 6,110,564 to Pontius, which is incorporated herein by reference, discloses a humidifier pad with multiple layers of slit and expanded paper laminated together. At least one of the paper layers comprises substantially nonwicking paper and the remaining layers comprise highly absorbent wicking paper.
Thus, the prior art humidifier pads are made of slit and expanded paper in combination with a reinforcing material, such as aluminum. However, in the prior art pads of this type, the layers are slit and expanded separately and then glued together separately.
The prior art also contains coated, expanded aluminum pads made using a manufacturing process in which aluminum foil is slit and expanded. Next, several layers of expanded aluminum are glued together using adhesives. A coating is then applied to the pad. Once the coating is cured, the pad is cut to the required dimensions.
As a result of this process, a very rigid humidifier pad is constructed. The color of the coating could be light brown, tan or light grey, and it helps to distribute water over a large surface of the humidifier pad to promote evaporation. However, the coating can release chemical compounds causing water discoloration and foaming, both of which are undesirable. Additionally, coated aluminum pads used in these applications are made using a relatively simple, but labor-intensive, manufacturing process. The coating slurry is a mix of several components that must be cured in an oven at high temperature. Very often this coating is also a cause of water discoloration when the pad is used.
Therefore, the need exists for an improved humidifier pad.